Not everything is perfect, of course, and storyboards do have some limitations. The storyboard version of Interface Builder isn’t as powerful as the old nib editor and there are a few handy things nibs can do that storyboards unfortunately can’t. You also need a big monitor, especially when you write iPad apps!
If you’re the type who hates Interface Builder and who really wants to create his entire UI programmatically, then storyboards are probably not for you. Personally, I prefer to write as little code as possible — especially UI code! — so this tool is a welcome addition to my arsenal.
And if you want to keep using nibs then go right ahead, but know that you can combine storyboards with nibs. It’s not an either-or situation.